1. Field of the Invention
The present invention relates to a servo control method and apparatus of a data storage device, and more particularly, to a method of controlling movement of a head in a data storage device, by which the head is moved to a safety region when an external impact of sufficient magnitude is applied to a disk drive, and a disk drive employing the method.
2. Description of Related Art
A typical example of a technique for controlling movement of a head in a data storage device is disclosed in Japanese Patent Publication No. 2002-109840, in which an error in determining a position of the head due to the external impact is reduced by detecting impact applied in directions of x- and y-axes to a surface of a disk by a sensor and calculating a component of the impact in a rotation direction on the basis of information on a present position of the disk read from the head.
Generally, a hard disk drive as a kind of the data storage device is adapted to read data from the disk or write the data on the disk by use of a magnetic head and thus to contribute to an operation of a computer system. A compact high-capacity and high-density hard disk drive has been developed to be employed as means for storing the data in a multimedia system.
The hard disk drive serves to magnetically write or read the information on or from a turning disk. Such a hard disk drive generally includes a disk assembly and an actuator assembly. The disk assembly includes at least one magnetic disk coupled to a hub rotated by an electric motor. The actuator assembly includes an actuator arm having one end supporting the components for writing or reading the data on or from the magnetic disk and the other end coupled to the motor which enables movement of the actuator arm.
As a result of the increased portability of personal computers, the hard disk drive is increasingly likely to be exposed to external impact. If the external impact is applied to the hard disk drive while the hard disk drive reads or writes the data from or on the disk, there is an ample possibility of the head contacting the surface of the disk. When the head contacts the surface of the disk, there is a damage to the disk or head.